Hi Hydo L,
Sitefinity 4 presents a whole new licensing system which allows you to test the product on your development domain but you will receive a trial message from time to time. You will be experiencing the trial message under your development domain because the domain is not licensed. There is no problem to continue your development under the development domain, but you will continue receiving a trial message every few clicks.
If you still want to test our product sales team
to have your trial period extended. After that you can purchase a license for our product and associate it with a domain of your choosing and have your live site function properly.
the Telerik team